Second-Order Filter
A second-order filter.
blockType: SubSystem
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Path in the library: |
Description
Block Second-Order Filter implements one of the following transfer functions depending on the parameter value Filter Type:
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Low-pass filter:
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High-pass filter:
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Bandpass filter:
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Notch filter:
Where
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— Laplace operator;
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— natural frequency, ;
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— attenuation coefficient (called Zeta in the block menu).
Features
The main characteristics of the block Second-Order Filter are:
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The input port accepts a vector from signals and implements filters. This feature is especially useful for designing controllers in three-phase systems ( );
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It is possible to initialize the filter states for the DC and AC Inputs specified.
Ports
Input
#
IN_1
—
filter input
scalar | vector
Details
The input signal of a second-order filter, specified as a scalar or vector.
| Data types |
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| Complex numbers support |
I don’t |
Output
#
OUT_1
—
filter output signal
scalar | vector
Details
The output signal of the second-order filter, returned as a scalar or vector.
| Data types |
|
| Complex numbers support |
I don’t |
Parameters
Main group
#
Filter Type —
selecting the filter type
Lowpass | Highpass | Bandpass | Bandstop (Notch)
Details
Determine the type of second-order filter: Lowpass, Highpass, Bandpass (by default) or Bandstop (Notch).
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Natural frequency fn, Hz — the natural frequency of the filter
Details
The natural frequency of the filter, set in Hz.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Damping ratio Zeta ( Q=1/(2*Zeta)) ) — attenuation coefficient of the filter
Details
The attenuation coefficient of the filter. Typically, the attenuation coefficient is in the range of 0 before 1.
The attenuation coefficient is related to the quality of the filter :
For a bandpass or notch filter, the bandwidth is at 3 dB is determined by the formula
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Sample time — sampling period
Details
Specify the sampling period of the block in seconds. Set the value 0 to implement a continuous block.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Initialize filter states — option to initialize filter states
Details
Select this option to initialize the filter states according to the parameters. AC initial input [Magnitude, Phase (deg), Frequency (Hz)] and DC initial input.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# AC initial input [Magnitude, Phase (deg), Frequency (Hz)] — the initial value of the variable component
Details
Specify the initial value of the variable component of the input signal: amplitude, phase in degrees, and frequency in Hz.
If the input signal is a vector ( signals), specify the matrix on , where each row of the matrix corresponds to a specific input.
Dependencies
To use this option, check the box Initialize filter states.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# DC initial input — the initial value of the constant component
Details
Specify the initial value of the constant component of the input signal. If the input signal is a vector, specify the vector on , where each value corresponds to a specific input.
Dependencies
To use this option, check the box Initialize filter states.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |